Flexible Chimney Liner

ABSTRACT

A flexible chimney liner is presented having a corrugation profile with an sheet strip width of about 110 mm to about 120 mm, preferably about 114 mm and a pitch of about 45 mm to about 55 mm, preferably about 50 mm.

FIELD OF THE INVENTION

This invention relates generally to chimney components and inparticular, to a flexible chimney liner.

BACKGROUND OF THE INVENTION

A chimney has a channel running its length for conveying exhaust gasesfrom a fireplace, furnace or boiler acting as a heating source.Combustion products in the form of hot exhaust gases rise up the channelto the outside. They are typically vented vertically to ensure that thehot gases flow smoothly upward. The venting medium passes through thestructure's roof to vent to the outside.

Over time it is not uncommon for the chimney venting medium to lose itssealing integrity, thereby allowing exhaust gasses to enter the livingspace. Rather than raising and rebuilding the chimney it is oftenadvantageous to create a new venting medium by inserting a flexiblechimney liner to reestablish sealing integrity.

Chimney liners are typically produced in lengths from 15 feet to 100feet. Due to their length they are coiled for shipping. Uncoiling thechimney liner at the job site often presents problems because it is verydifficult to uncoil the liner. Uncoiling the liner is time consuming andthe uncoiled liner retains some memory and does not become completelystraight.

Illustrated in FIG. 1, when the chimney liner is inserted into theexisting chimney channel which may contain one or more offsets, it oftenrequires “fishing” the liner through the channel. This requires that theliner be capable of flexing to pass an offset without becomingpermanently distorted.

Additionally, the chimney liner must be able to coil for shippingwithout kinking The greater the flexibility the liner can achievewithout distortion the wider the range of retrofits with which it can beused.

Accordingly, there is still a continuing need for improved flexiblechimney liner designs. The present invention fulfills this need andfurther provides related advantages.

BRIEF SUMMARY OF THE INVENTION

Described below is a novel chimney liner design that retainssignificantly less coiling memory than existing liners so that ituncoils much easier and once uncoiled remains straight. The novel designalso provides greater flexibility without permanent distortion thanknown designs.

Additionally, its novel profile provides greater crush resistance thanknown chimney liners.

In a preferred form the chimney liner has a corrugation profile with ansheet strip width W of about 110 mm to about 120 mm, preferably about114 mm and a pitch P of about 45 mm to about 55 mm, preferably about 50mm.

Other features and advantages of the present invention will be apparentfrom the following more detailed description of the preferredembodiments, taken in conjunction with the accompanying drawings whichillustrate, by way of example, the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the present invention. These drawings are incorporatedin and constitute a part of this specification, illustrate one or moreembodiments of the present invention, and together with the description,serve to explain the principles of the present invention.

FIG. 1 is a side cutaway view of an installed flexible chimney liner.

FIG. 2 illustrates a section of flexible chimney liner duringfabrication from a corrugated metal sheet.

FIG. 3 is a side view of a section of flexible chimney liner.

FIG. 4 is a side view of the lock seam of FIG. 2

FIG. PA-1 is side view of a known corrugation profile

FIG. 5 is a side view of the corrugation profile Z of FIG. 2.

Other features and advantages of the present invention will be apparentfrom the following more detailed description of the preferredembodiments, taken in conjunction with the accompanying drawings whichillustrate, by way of example, the principles of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As required, detailed embodiments of the present invention aredisclosed; however, it is to be understood that the disclosedembodiments are merely exemplary of the invention that may be embodiedin various forms. The figures are not necessary to scale, and somefeatures may be exaggerated to show details of particular components.Therefore, specific structural and functional details disclosed are notto be interpreted as limiting, but merely as a basis for the claims andas a representative basis for teaching one skilled in the art tovariously employ the present invention. Where possible, like referencenumerals have been used to refer to like parts in the severalalternative embodiments of the present invention described herein.

A flexible chimney liner 2 is fabricated using known technology, forexample, by twisting a corrugated sheet 4, for example, a metal sheet,around a tool (not shown). FIG. 2 illustrates a section of the chimneyliner 2 during fabrication from a corrugated metal sheet 4.

The flexible chimney liner 2 includes a wall 20 formed from thecorrugated metal sheet 4. The metal sheet 4 has opposing first andsecond edges extending longitudinally along the metal sheet 4. The wall20 includes a seam, such as lock seam 6, formed by abutting portions ofthe first and second edges. The lock seam 6 extends helically about andalong a length of the wall 20. The metal sheet 4 has an interior wallside and an opposing exterior wall side. The interior wall side definesan inner wall surface 22 of the chimney liner 2, and the exterior wallside defines an outer wall surface 24 of the chimney liner 2. The metalsheet 4 has a sinusoidal profile defining the corrugation peaks 26 andcorrugation valleys 28 of the chimney liner 2 (FIG. 3).

The novel profile of the corrugations (described in detail below) is notlimited by the metal sheet material or the finished liner insidediameter DN (FIG. 3).

In its preferred form, the corrugated metal sheet 4 is aluminum orstainless steel having a width of about 110 mm to about 120 mm,preferably about 114 mm. After fabrication the flexible chimney liner 2preferably has a finished inside diameter DN of about 127 mm to about305 mm.

FIG. 3 is a side view of the fabricated flexible chimney liner 2. Lockseams 6 are formed during the manufacturing process from a sheet firstedge and a sheet second edge in known fashion, for example, asillustrated in FIG. 4. The distance from lock seam to lock seam isreferred to as the pitch P.

To aid in understanding the novelty of the claimed profile, comparisonwill be made to a known flexible chimney liner, illustrated in FIG.PA-1. The height H of a known chimney liner corrugation is 3.2 mm(0.126″). The angle α of the corrugations, determined by facingcorrugation walls 8, 8′, is 53.8 degrees. The width of the corrugationCW, is 3.099 mm (0.122″), and the radius R of the corrugation is 1.346mm (0.053″). The pitch P is 73 mm (2.874″).

In manufacturing a chimney liner, for a given sheet strip width W, thepitch P is determined by the corrugation height H; corrugation width CW;angle of the corrugations α; or a combination of each. Therefore, if apitch P change is desired for a given sheet width W, the corrugationheight H; and/or the corrugation width CW; and/or the angle of thecorrugations α; or some combination of those parameters would need to bemodified.

The relationship of the sheet strip profile parameters (radius R, widthW, angle of the corrugations α, and height H) directly impact the pitchP. There is a maximum height H of any profile beyond which themanufacturing tooling becomes too weak to form the sheet strip properlywithout breaking. However, reducing the height H will make the linerless flexible.

There is also an optimal angle of the corrugations α. As the angle α isreduced the strip formation becomes more difficult while if the angle αis increased too much the liner is more likely to kink when coiled.

Likewise the radius R has a direct impact on the manufacturing process.The radius R has a value beyond which it cannot be decreased withoutmaking the tooling too weak to form the profile without breaking.

Unexpectedly, with a sheet strip width W of about 110 mm to about 120mm, preferably about 114 mm, a pitch P of about 45 mm to about 55 mm wasfound to provide optimal manufacturing and finished chimney linercharacteristics.

FIG. 5 is an enlarged cross sectional view of a portion Z (FIG. 3) of alength of the novel flexible chimney liner 2 constructed in accordancewith an aspect of the present invention.

In developing the novel profile described below it was unexpectedlyfound that as the angle of the corrugations α approaches 0 degrees(parallel) the more favorable the chimney liner flexibilitycharacteristics become. Significant improvement over known corrugationgeometry was found when the angle of the corrugations α was less than orequal to about 10 degrees. About a 6 degree angle of corrugations αachieved superior characteristics.

When corrugation height H is smaller the chimney liner flexibility isreduced and when it is greater the chimney liner becomes weaker. Optimalcorrugation height H providing the best balance of flexibility tostrength was found to be from about 4.648 mm (0.183″) to about 4.826 mm(0.190″) with about 4.65 mm being preferred.

As the pitch P increases the ability to manufacture operativelyacceptable smaller diameter liners is reduced As the pitch P decreasesthe liner becomes less flexible. Optimal pitch P providing the bestbalance of flexibility and the ability to run smaller diameters DN isabout 45 mm to about 55 mm and most preferably about 50 mm (1.97″).

The optimal corrugation radius R is about 1.27 mm to about 1.52 mm andmost preferably about 1.397 mm (0.55″). Preferably the lock seam 6 isabout 2.5 mm wide.

As noted above, optimal chimney liner characteristics can be obtainedwith a sheet strip width W of about 110 mm to about 120 mm, preferablyabout 114 mm and a pitch P of about 45 mm to about 55 mm, preferablyabout 50 mm. Additional manufacturing benefit is obtained with alsohaving an angle of corrugation a less than or equal to about 10 degrees,preferably about 6 degrees, a corrugation height H from about 4.648 mmto about 4.826 mm, preferably about 4.65 mm, a corrugation width CW ofabout 5.8 mm, and a corrugation radius R of about 1.27 mm to about 1.52mm, preferably about 1.397 mm (0.55″) .

Using the novel profile parameter discussed above significantly andunexpectedly strengthens the chimney liner. Tests have shown the novelprofile will hold 400 pounds per square foot as compared to 150 poundsper square foot with known profile parameters. The novel profile alsoproduces a significant increase in flexibility, achieving asignificantly greater degree of flex without kinking than that of knownprofiles. Once corrugations are kinked the chimney liner is ruined.

Although the present invention has been described in connection withspecific examples and embodiments, those skilled in the art willrecognize that the present invention is capable of other variations andmodifications within its scope. These examples and embodiments areintended as typical of, rather than in any way limiting on, the scope ofthe present invention as presented in the appended claims.

What is claimed is:
 1. A chimney liner having a profile comprising asheet strip width of about 110 mm to about 120 mm and a pitch of about45 mm to about 55 mm.
 2. The chimney liner of claim 1 further comprisinga corrugation height of about 4.648 mm to about 4.826 mm and an angle ofcorrugation less than or equal to about 10 degrees.
 3. The chimney linerof claim 1 wherein the sheet strip width is about 114 mm and the pitchis about 50 mm.
 4. The chimney liner of claim 2 wherein the corrugationheight is about 4.65 mm and the angle of corrugation is about 6 degrees.5. The chimney liner of claim 3 wherein the corrugation height is about4.65 mm and the angle of corrugation is about 6 degrees.
 6. The chimneyliner of claim 1 further comprising a corrugation width of about 5.8 mm.7. The chimney liner of claim 1 further comprising a corrugation radiusof about 1.27 mm to about 1.52 mm.
 8. The chimney liner of claim 1further comprising an inside diameter of about 127 mm to about 305 mm.9. A chimney liner having a profile comprising a sheet strip width ofabout 110 mm to about 120 mm, a pitch of about 45 mm to about 55 mm, anangle of corrugation less than or equal to about 10 degrees, acorrugation height from about 4.648 mm to about 4.826 mm, a corrugationwidth of about 5.8 mm, and a corrugation radius of about 1.27 mm toabout 1.52 mm.
 10. The chimney liner of claim 9 wherein the sheet stripwidth is about 114 mm and the pitch is about 50 mm.
 11. The chimneyliner of claim 9 wherein the corrugation height is about 4.65 mm and theangle of corrugation is about 6 degrees.
 12. The chimney liner of claim10 wherein the corrugation height is about 4.65 mm and the angle ofcorrugation is about 6 degrees.13. The chimney liner of claim 10 furthercomprising a corrugation width of about 5.8 mm.
 13. The chimney liner ofclaim 9 further comprising an inside diameter of about 127 mm to about305 mm.
 14. A chimney liner manufacturing process comprising the stepsof: forming corrugations in a sheet strip; twisting and seaming thesheet strip to form a chimney liner; wherein the corrugations form achimney liner profile comprising a sheet strip width of about 110 mm toabout 120 mm and a pitch of about 45 mm to about 55 mm.
 15. The processof claim 14 wherein the sheet strip width is about 114 mm and the pitchis about 50 mm.
 16. The process of claim 14 wherein the chimney linerprofile further comprises a corrugation height of about 4.648 mm toabout 4.826 mm and an angle of corrugation less than or equal to about10 degrees.
 17. The process of claim 15 wherein the chimney linerprofile further comprises a corrugation height of about 4.648 mm toabout 4.826 mm and an angle of corrugation less than or equal to about10 degrees.
 18. The process of claim 15 wherein the chimney linerprofile further comprises an inside diameter of about 127 mm to about305 mm.
 19. The process of claim 14 wherein the chimney liner profilefurther comprises an inside diameter of about 127 mm to about 305 mm.20. The process of claim 14 wherein the chimney liner profile furthercomprises an angle of corrugation less than or equal to about 10degrees, a corrugation height from about 4.648 mm to about 4.826 mm, acorrugation width of about 5.8 mm, and a corrugation radius of about1.27 mm to about 1.52 mm.